According to a study published yesterday in PLoS ONE, you're more likely to respond with a yawn to a family member's yawn than to a friend's yawn. (Be honest, how many of you just yawned?)

But here's the really interesting bit: while "yawn contagion" was shown to be highest between kin, it was still higher between friends than it was between acquaintances, and higher between acquaintances than between strangers — lending credence to the long-standing hypothesis that our predilection to "catching" yawns is a manifestation of our empathetic nature (our tendency to experience empathy follows the exact same pattern of regression). [PLoS ONE]